TLD Detectors Research Articles

Analysis of Scattered Radiation Dose in Cardiac Catheterization Examination in the Cathlab Room Using TLD

The problem: About 75% of the information humans receive visually or through the eyes. However, the eye cannot detect all types of light, including X-ray radiation. There are parts of the human body organs are very sensitive to X-ray radiation, because of the risk of damaging tissues and triggering causing ery, infertility or cataracts. Today, X-rays have become the backbone of the development of radiology equipment, especially for producing. One of them is C-Arm equipment technology, which is able to image three-dimensional patient objects in real time with fluoroscopy techniques. This study aims to obtain and evaluate the effective radiation dose received by medical personnel working in the cathlab room area when radiation workers during cardiac catheterization is performed. Observations were made in 10 radiation measurement areas, namely the radiographer operator area, the area in and out of medical personnel, the area in and out of patients, the Pb glass area in the operator room, the Pb glass area in the Cathlab examination room, the area where TLD measurements are placed waist-high doctors, nurses and radiographers work during the installation of the heart ring, the floor area near the X-ray source, and the wall area in the Cathlab examination room. The main tool uses C-Arm modality, and TLD detector chips. The object of observation is the radiation source area consisting of one doctor, one radiographer and one nurse. Catheterization was performed on 10 patients with different examination times. Research results: operator area; the effective dose received was 0.000 mSv, doctors ranged from 1.136 to 3.608 mSv, while nurses ranged from 0.194 mSv to 2.270 mSv, while radiographers ranged from 0.074 mSv to 0.126 mSv, while patient entrance and exit areas ranged from 0.00 mSv to 0.0127 mSv, while nurses in and out of medical personnel ranged from 0.005 mSv to 0.057 mSv, Measurements on the floor near the radiation source/floroscopy range from 0.036 mSv to 0.074 mSv. Cathlab indoor wall measurement results range from 0.031 mSv to 0.103 mSv. Within 1 year, the dose in the operator room is 0.00 mSv, the dose received by doctors ranges from 230.4 to 1209.5 mSv/hour, radiographers between 128.2 mSv to 1812.4 mSv and nurses between 115.2 mSv to 2448.2 mSv. In the area of the patient entrance and exit between 0.00 mSv to 38.8 mSv, the area of the patient entrance and exit between 72.00 mSv to 82.2 mSv, and the floor area near the radiation source/floroscopy between 518.2 mSv to 1065.2 mSv, as well as the inner wall area of the cathlab chamber between 44.6 mSv to 148.32 mSv. It was found that; The effective dose received in one year received by doctors, nurses and radiographers who work close to radiation sources (floroscopy) results are higher than the dose value set by PERKA BAPETEN No. 8 of 2011 which is 20 mSv and ICRP 203 which is 500 mSv per year.

Exposure to ionizing radiation by service personnel working with cyclotrons used to produce radiopharmaceuticals in PET diagnostics.

While working with cyclotrons used for the production of radiopharmaceuticals, workers can experience significant exposure to the adverse effects of ionizing radiation. The aim of this paper was to determine the typical level of such exposure received by such personnel while servicing cyclotrons. Exposure was assessed using TLD detectors placed in an anthropomorphic phantom, as well as dose meter to determine whole body and eye lens exposure. The phantom was placed in locations receiving the greatest exposure to ionizing radiation during service activities. The time spent by employees during servicing was assessed based on routine visits by service technicians. The obtained results were compared with readings of detectors worn by employees during service activities. The highest equivalent doses in the thoracic area were found to be received by the lungs (211.16 μSv/year). In the head and neck area, the highest dose was measured in the eye lens (3410 μSv/year). The effective dose for the whole body was found to be 1154.4 μSv/year, based on the phantom, and 149 μSv per service visit (1192 μSv/year), based on the dose meters carried by the workers. Service workers are exposed to significant doses of ionizing radiation, representing a clear radiological protection issue. To reduce exposure to eye lenses, it is recommended to use protective goggles when working with highly-radioactive elements. Int J Occup Med Environ Health. 2022;35(6):753-60.

ОЦЕНКА ДОЗ ОБЛУЧЕНИЯ ХРУСТАЛИКА ГЛАЗА И КОЖИ ПЕРСОНАЛА В СОВРЕМЕННЫХ МЕДИЦИНСКИХ ТЕХНОЛОГИЯХ

Background: The widespread use of radiation technologies in medicine puts some new issues on the agenda in the field of radiation safety and protection of the personnel. This primarily relates to the advanced methods of diagnosis and treatment with the use of X-ray technology and radiopharmaceuticals (RPhP) under conditions of occupational exposure to low-intensity scattered radiation. The applied personal protective equipment reliably assures that the effective dose is not exceeded, but does not ensure compliance with the standards for the lens of the eye and the irradiated areas of the skin. Purpose: This study is to evaluate, in the advanced medical technologies, the doses to the lens of the eye and skin of the personnel working in a low-intensity radiation field and in direct contact with radioactive sources. Materials and methods: To evaluate the doses, TLD detectors were used for the purpose of dose assessment to the lens of the eye НР(3) and the skin of the fingers НР(0,07). The data of international studies are involved. Results: In conditions of a significant reduction in the limits of equivalent doses to the lens of the eye, up to 20 mSv the assessment of the radiationlevels of the latter, based on data on the effective dose, becomes impossible. In addition, there are facts of damage to the lens of the eye at much lower levels of radiation than previously thought. The paper evaluates the existing exposure to the lens of the eye for some medical technologies, both according to the published data and according to the results of our own research. It is shown that the existing radiation levels can significantly exceed 20 mSv per year (up to 0.2 mSv per operation) and it is impossible to exclude the stochastic nature of lens damage. Data on the levels of skin irradiation in X-ray surgical technologies and when using RPhP based on 18F (up to 200 mSv per year for finger biting) are also provided.). New approaches to rationing activities with radiation sources are considered based on the assessment of the workload: the number of manipulations, the activity used. Conclusion: The research data confirm the relevance of the problem of exposure to the lens of the eye and the skin of the personnel working in the field of scattered radiation of low intensity. Along with the assessment of the equivalent doses to these organs, epidemiological studies should be conducted for the purpose ofassessment and development of adequate radiation protection measures for the lens of the eye and the irradiated parts of the skin (hands)

Response of a TLD badge to the new operational quantity Hp(θ): Monte Carlo approach

In 2020, the International Commission on Radiation Units and Measurements’ Report Committee 26 (RC 26) proposed new operational quantities to be used in personal monitoring for external radiation. METROBRAS is a Brazilian laboratory that uses a TLD-based personal dosimeter calibrated in terms of the personal dose equivalent, Hp(10, θ). In this paper, an evaluation of the METROBRAS personal dosimeter to the new operational quantity personal dose, Hp(θ), was performed. This assessment was based on the determination of Hp(10, θ) and Hp(θ) using Monte Carlo simulation. The basic personal dosimeter design includes three CaSO4:Dy plus polytetrafluoroethylene (PTFE) detectors sandwiched between different filters inside of an acrylic badge. The determination of the relative response for six X-ray qualities and for gamma-rays from Cs-137 (662 keV) was carried out using the Monte Carlo transport code MCNPX. TLD detectors, filters and the plastic badge were simulated on the surface of a water ISO phantom with 30 cm × 30 cm x 15 cm with PMMA walls. The effect of the direction of radiation incidence has been determined for angles of 0° (anterior-posterior, AP), ±45° and ±60°. The new Hp(θ) quantity affected the relative energy and angular response of the TLD badge mainly for the low photon energies with maximum factors of ∼1.94 and ∼2.91 for 33 keV and 24 keV, respectively. The TLD-badge exhibited not only photon energy but also angular dependence, that was larger for Hp(θ). The major differences between the relative angular responses with respect to the response at 0° were found for the exposures at ± 60°. To comply with the requirements of the new quantity, an upgrade on the calculation algorithm and a new design of the filter set (that allows energy discrimination) should be made. The information provided by the Monte Carlo data helped to predict the METROBRAS badge response to the new operational quantity Hp(θ).

Quality control measures of thermoluminescent dosimetry system used in environmental radiation monitoring

Objective To discuss the quality control measures of the thermoluminescent dosimetry system and to verify its propriety of when used in environmental radiation monitoring. Methods The quality control measures included the stability test, the dispersibility screening and the uncertainty evaluation of measurement results of the TLD reader and TLD detector, in addition, the environmental radiation accumulated dose monitoring results obtained by the high pressure ionization chamber were compared with those by the thermoluminescent dosimetry system. Results The variation range of TLD reader’s light source coefficient is within 0.070~0.073 during the preheating and measuring process, which meets the requirements of stability; The χ 2 value of the TLD detector is 2.088, which obeys the normal distribution; The thermoluminescent dosimetry system’s nonlinear response, coefficient of variation and energy response meet the measurement requirements; There is a deviation of −6.58% the largest between the cumulative dose obtained by TLD and the high pressure ionization chamber. Conclusion The quality control measures discussed in this paper can be used as a reference for similar thermoluminescent dosimetry system. Our system has passed all the tests and can meet the environmental radiation cumulative dose monitoring requirements. 摘要： 目的 探讨热释光测量系统的质量控制方法, 验证热释光测量系统能否准确有效的用于环境辐射水平监测。 方法 采取的环境辐射监测用热释光测量系统质量控制方法包括热释光测量系统的稳定性检验、热释光探测器的分 散性筛选、测量结果不确定度评定, 并与高气压电离室测量方法进行对比。 结果 读出器预热及测读过程中光源系数 变化范围在 0.070~0.073, 稳定性符合使用要求; 热释光探测器的 χ 2 值为 2.088, 服从正态分布;热释光测量系统满足 非线性响应、变异系数和能量响应的计量要求; 热释光累积剂量测量结果与高气压电离室相比偏差最大 −6.58%。 结论 本实验室采取的质控措施可作为同类热释光测量系统的质控措施的参考;本实验室的热释光测量系统通过了 各项检验, 满足环境辐射累积剂量监测的使用要求。

Measurement of Neutron Flux at Thermal Column Using Gold Foil Activation Analysis and TLD Detector: Technical Review

The thermal column at the TRIGA PUSPATI (RTP) research reactor can produce thermal neutron. However, the optimization on the thermal neutron flux produced should be performed to gain a sufficient thermal neutron for boron neutron capture therapy purpose. Thus, the objective of this review is to optimize the thermal neutron flux by designing the collimator with different materials at the thermal column. In order to fulfil the requirement, set by the IAEA standard, the study of Boron Neutron Capture Therapy (BNCT) around the world was being reviewed to study the suitable measurement, material, design, and modification for BNCT at the thermal column of TRIGA MARK-II, Malaysia. Initially, the BNCT mechanisms and history was review. Then, this paper review on the design and modifications for BNCT purpose around the world. Based on this review, suitable material and design can be used for the BNCT in Malaysia. Moreover, this paper also reviews the current status of BNCT at the RTP with the measurement of the thermal neutron flux was conducted along the thermal column at 250 kW. The thermal column of RTP was divided into 3 phases (Phase 1, Phase 2 and Phase 3) so that an accurate measurement can be obtained by using gold foil activation method. This value was used as a benchmark for the neutron flux produced from the thermal column. The reviewed demonstrated that the final thermal neutron flux produced was significantly for BNCT purpose.

On the possibility of photo- and photo-thermal depletion of deep traps in α-Al2O3-δ

In this study, we explored the possibility of photo- and photo-thermal depletion of deep traps in anion-deficient corundum (α-Al2O3-δ) crystals and luminescent storage dosimeters on their basis. As a result of repeated normal use or a single exposure to high-dose radiation, these traps become filled, which reduces significantly the informative response of thermally and optically stimulated luminescence (TL and OSL) due to the depletion of the main dosimetric trap. It has been found that effective photodepletion of the deep trap causing the 830 K TL peak, whose filling affects the informative TL and OSL responses most of all, is only possible in α-Al2O3-δ crystals and unpacked TLD-500 detectors on their basis. In the majority of cases, including practically important ones associated with the restoration of the dosimetric properties of widely employed α-Al2O3-δ dosimeters, photothermal depletion proves to be more effective.

The peculiarities of anion vacancy distribution and the relationship between their concentration and the Tld-500 detector Tl output

A procedure has been developed for estimating the uniformity of anion vacancy distribution in TLD-500 detectors on the basis of anion-deficient corundum single crystals. Vacancy distribution topograms were constructed for TLD-500 detectors with different sensitivities to irradiation. Analysis of the topograms provided correlations between average anion vacancy concentrations and thermoluminescent (TL) yields in the main peak with a maximum at 450 K. To confirm the pattern of regularities, the effects of high-temperature annealing of TLD-500 samples in air at T = 1700 K were studied depending on its duration. Increasing the annealing time from 40 to 105 minutes was found to correlatedly reduce the anion vacancy concentrations and TL-yields in the basic and high-temperature peaks at 450 and 830 K, respectively.

OA237] The output factor measurements of cyberknife system using various detectors

Purpose In Stereotactic Radiosurgery, the extremely high radiation dose is delivered to the target in a single or few fractions using narrow radiation fields. The radiation fields are collimated with 12 fixed circular collimators ranging from 5 to 60 mm in diameter in CyberKnife which is a robotic radiosurgery system. The accuracy of the output factors directly affects the accuracy of treatment delivery to the patients. The output factor (OF) measurement of small fields is very problematic and the small field measurements are more sensitive to physical properties of detectors. The aim of the present study is to perform the relative OF measurements of 12 fixed collimators in CyberKnife system using different detectors. Methods In this study, the OF measurements of 12 fixed collimators were made with CyberKnife system at maximum dose depth in water equivalent RW3 slab phantom using PTW 60019 microDiamond, PTW 31014 0.015 cc PinPoint, PTW 31010 0.125 cc Semiflex, EBT3 Gafchromic film and GR-200A TLD. All detectors were positioned at the center of the radiation field with the point laser from treatment head. The measured data were compared with Monte Carlo (MC) factors. Results The OF values measured at 30 mm and greater collimator sizes were found similar for all detectors. The OF values decrease rapidly as the collimator size becomes smaller. The measured data with TLD and microDiamond detector at the smallest collimator sizes such as 7.5, 10, 12.5 and 15 mm were found very similar with MC factors. Conclusions 0.125 cc Semiflex ion chamber may lead to large uncertainties in the OF measurements for the smallest collimator sizes. TLD and microDiamond detector show similar results for all collimator sizes except 5 mm. TLD is an utilizable dosimetric tool in the small field OF measurements by means of its small active volume.

P100] Calculations of dosimetric parameters from depth dose curve of electron beams, using radiophotoluminescent and thermoluminescent dosimeters

Purpose The aim of this study was to calculate the dosimetric parameters derived from percent depth dose curves by using RPL-GD and TLD-100 detectors for high-energy electron beams. Methods In this study, Monte Carlo simulation code MCNP5 was using to calculate the percent depth dose (PDD) in water phantom for 9, 12, 16 and 20 electron beam energies with utilizing the Radiophotoluminescent (FD-7glass series) and Thermoluminescent (TLD-100) materials. Results We found a good agreement with literature for Monte Carlo calculations parameters derived from the PDD curve such as various ranges R 100 , R 90 , R 80 , R 50 and R p and energies specification such us most probable energy E p , o and mean incident energy E 0 . Conclusion In conclusion, RPL-GD and TLD-100 dosimeters are a very useful detector for routine QA checks for electron therapy [1] .

A LiF and BeO TLD based microdosimeter for space radiation risk assessment of astronauts

The ratio of thermoluminescence glow curve area of BeO and LiF dosimeters was found to be proportional to average LET and quality factor (Q) of impinging mixed radiations. Using this phenomenon and widely available Thermoluminescence Dosimeter TLD-700 (7LiF: Mg,Ti) and BeO (Thermolux 995) chips a TLD-Microdosimeter (LiBe-14) emulating a much larger gas-filled Tissue Equivalent Proportional Counter (TEPC) was developed. The TEPC is an essential device of space radiation dosimetry widely used by international space agencies. The LiBe-14 is capable of assessing the LETTissue (5–300 keV/μm), quality factor Q (1–30) and associated dose equivalent H (0.1–1000 mSv) of any mixed radiation fields of interest, including space radiations predominant in Low Earth Orbit (LEO) environment. The TLD microdosimeter was calibrated using the secondary radiation fields produced by bombarding a 25 cm × 25 cm × 35 cm polystyrene phantom with 81, 119, 150, 177, 201 and 231 MeV protons from a Proton Therapy Medical Cyclotron. The TLD pair (BeO/LiF) was attached to the TEPC and placed lateral to the proton beam. The characteristics of space radiation inside the spacecraft are complex. Hence, personal dosimetry of astronauts in the space habitat is performed using “multi-element” dosimeters made of different types of TLD and CR-39 plastic nuclear track detector (PNTD). The TLD and PNTD are used to assess the sparsely (low LET) and densely (high LET) ionising radiation component respectively. This report elucidates the feasibility of LiBe-14 microdosimeter for the estimation of overall dose equivalent and “risk of exposure induced death” (REID) of astronauts working in LEO space stations.

High-temperature thermoluminescence of anion-deficient corundum and its connection with intrinsic defects and impurities

Anion-deficient corundum and TLD-500 detectors on their basis were studied for a possible correlation between the thermoluminescence (TL) yield in the high-temperature TL peak at 830 K and the transformation of intrinsic defects and contents of impurities. Only 40– 60% of TLD-500 detectors were found to have 830 K TL peak. The efficiency of thermally stimulated direct conversion of F and F+ centers in the 800–930 K region depends on the presence of TL peak at 830 K. Obtained data point to the quenching role of the Ti impurity in the formation of the 830 K TL peak. Also, these data provide indirect evidence of association of the 830 K TL peak with Cr3+ ions.

Cyclotron production of F18 in TLD-500 and other new usage potentialities of anion-deficient corundum

Samples of standard TLD-500 detectors on the basis of anion-defective corundum (α-Al2O3-δ) were found to emit gamma radiation when irradiated with 5.7 MeV protons. The objective of this study was to identify the nature of the induced radioactivity assuming the 18O (p, n)18F reaction as highly probable and to study the prospects for its new practical applications.

Thermally stimulated transformations of luminescence centers in TLD-500 detectors and their correlation with TL properties

TLD-500 detectors based on anion-deficient corundum with the 830 K TL peak and without it have been studied comprehensively for thermoluminescence in an extended temperature range of 300–1000 K, changes in the concentrations of active centers and their photoluminescence as a function of the annealing temperature up to 1400 K along with corresponding thermostimulated changes in the TL spectra and TL yields in the main peak at 450 K, including in individual bands. Such a comprehensive approach has enabled us to not only relate the observed TL with thermally stimulated transformations of centers and their interactions, but also to understand more profoundly the nature of the thermally stimulated processes in both the main and high-temperature peaks at 450 and 830 K, respectively.

Photoluminescence dose dependences of F and F+-centers in TLD-500 detectors

The photoluminescence spectra of TLD-500 detectors were measured before and after γ-irradiation in the 1–50 Gy range. After irradiation, the PL spectrum at the excitation with Eexc = 4.8 eV features an additional wide band with the maximum at 550 nm associated with the formation of aggregate F22+-centers. The intensity of the emission of this band increases with a growing dose. Dependences of the intensities of emission of F and F+-centers on the dose was studied. A big difference in radiation-induced transformation of these centers is caused by competition of the processes of creation of aggregate centers and interconversion (F ↔ F+).

High-temperature thermoluminescence of anion-deficient corundum and its connection with Ti impurity

Absract Anion-deficient corundum (α-Al2O3-δ) was studied for a possible correlation between the TL yield in the high-temperature peak at 830 K and the contents and transformation of intrinsic defects and impurities. Only 40–60% of TLD-500 detectors based on α-Al2O3-δ were found to have a 830 K TL peak. Increasing the concentration of the titanium impurity from 7·10−4 to 21·10−4 wt% was found to reduce the TL yield in the 830 K peak to an undetectable level. Similar variations of Mg, Si, Ca, Cr and Fe impurity concentrations did not allow us to reveal correlations with the TL yield at 830 K. Nevertheless, the measurements of active center concentrations at step-annealing from 300 to 1400 K suggest that the anion deficiency and related cation interstitials participate, as well as chromium ions, in the formation of the 830 K TL peak. Presumably, UV emission with a maximum at 4.1 eV observed in the 830 K TL peak may be caused by transitions from higher excited states in F+, F or other centers, including impurities and multi-component centers with intrinsic defects.

SU-G-BRB-15: Verifications of Absolute and Relative Dosimetry of a Novel Stereotactic Breast Device: GammaPodTM

Purpose: A dedicated stereotactic breast radiotherapy device, GammaPod, was developed to treat early stage breast cancer. The first clinical unit was installed and commissioned at University of Maryland. We report our methodology of absolute dosimetry in multiple calibration conditions and dosimetric verifications of treatment plans produced by the system. Methods: GammaPod unit is comprised of a rotating hemi-spherical source carrier containing 36 Co-60 sources and a concentric tungsten collimator providing beams of 15 and 25 mm. Absolute dose calibration formalism was developed with modifications to AAPM protocols for unique geometry and different calibration medium (acrylic, polyethylene or liquid water). Breast cup-size specific and collimator output factors were measured and verified with respect to Monte-Carlo simulations for single isocenter plans. Multiple isocenter plans were generated for various target size, location and cup-sizes in phantoms and 20 breast cancer patients images. Stereotactic mini-farmer chamber, OSL and TLD detectors as well as radio-chromic films were used for dosimetric measurements. Results: At the time of calibration (1/14/2016), absolute dose rate of the GammaPod was established to be 2.10 Gy/min in acrylic for 25 mm for sources installed in March 2011. Output factor for 15 mm collimator was measured to be 0.950. Absolute dose calibration was independently verified by IROC-Houston with a TLD/Institution ratio of 0.99. Cup size specific output measurements in liquid water for single isocenter were found to be within 3.0% of MC simulations. Point-dose measurements of multiple isocenter treatment plans were found to be within −1.0 ± 1.2 % of treatment planning system while 2-dimensional gamma analysis yielded a pass rate of 97.9 ± 2.2 % using gamma criteria of 3% and 2mm. Conclusion: The first GammaPod treatment unit for breast stereotactic radiotherapy was successfully installed, calibrated and commissioned for patient treatments. An absolute dosimetry and dosimetric verification protocols were successfully created.

Tanggapan Dosimeter Lensa Mata Personal Menggunakan TLD-900 (CaSO4:Dy) pada Medan Radiasi Beta dan Foton

Manufacturing and testing of eye lens dosemeter have been carried out using TLD detector CaSO4: Dy in beta radiation field. The results indicated a good response in reproducability and homogeneity with the acquisition of the response variations below 10%. The response to variations in beta energy indicated that the beta with energy below 0,7 MeV, represented by 85 Kr, could not penetrate the filter layer, while high energy beta of 90 Sr/ 90 Y was able to penetrate the filter and provided response to 137 Cs of 0.44 ± 0.07. Response to incidence angle of beta radiation showed dependence on the angle of incidence of irradiation. The response indicates the photon energy dependence on the energy below of 100 keV with angle response of radiation incidence on the energy 65 keV showed good results with the difference in readings against the irradiation of 0° maximum 20 %.

Dosimetry verification on VMAT and IMRT radiotherapy techniques: In the case of prostate cancer

Radiotherapy treatment depends on the accuracy of the dose delivery to patients, the purpose of the study is to verify the dose in IMRT and VMAT technique in prostate cancer cases correspond to TPS dose using phantom base on ICRU No.50. The dose verification of the target and OAR was performed by placing the TLD Rod LiF100 and EBT2 Gafchromic film at slab hole of pelvic part of the Alderson RANDO phantom for prostate cancer simulation. The Exposed TLDs was evaluated using the TLD Reader Harshaw while EBT2 film was scanned using Epson scanner. The point dose measurements were compared between planned dose and measured dose at target volume and OAR. The result is the dose difference at target volume, bladder and rectum for IMRT and VMAT are less than 5%. On the other hand, the dose difference at the Femoral head is more than 5% for both techniques because the location of OAR already in low gradient dose. Furthermore, the difference dose of the target volume for IMRT technique tends to be smaller than VMAT either for TLD and EBT2 film detectors. From the measurement showed that the delivered dose on the phantom simulation match with ICRU No.50 criteria.

Accumulation features and TL of TLD-500 detectors in a wide temperature range at pulsed and continuous high-dose irradiation

The results of a comparative research of thermoluminescence (TL) of TLD-500 detectors based on anion-defective corundum irradiated with continuous and pulsed X-ray and pulsed electron beams in a range of doses of 0.3 ÷ 107 Gy, dose rates of 0.02–2.6·1011 Gy/s, and in a temperature range of 300–950 K are presented. It is found that, in contrast to continuous irradiation, upon pulsed irradiation with a duration of 10 ns and dose rate of PP ≥ 5·106 Gy/s, the first linear region of dose dependences for TL peaks at 450, 580 and 830 K is, instead of saturation, followed by a second one with a smaller slope at doses near 2, 200 and 103 Gy. Moreover, the slope of the second region increases with growing PP. It was also found that dose dependence for the peak at 830 K in the area of the first linear region at 10–103 Gy remains invariable at PP ≤ 1010 Gy/s. It is shown that the upper limit of doses registered by TLD-500 detectors can be increased to 2·103 and 6·106 Gy for continuous and pulsed irradiation, respectively. New broadband UV luminescence with a maximum hν = 4.1 eV and half width H = 0.85 eV was registered within the TL peak spectrum at 830 K. Besides, the optical depletion spectrum in which a single band with hν = 5.2 eV and H = 1.6 eV is observed was investigated for a trap causing a peak at 830 K.